Nearly a third of young teenage girls have been sexually harassed online by children their own age.
Research by charity Childnet found 31 per cent of female 13 to 17-year-olds had been targeted with unwanted sexual attention over the internet, compared with 11 per cent of boys.
One in 10 young people reported receiving threats of sexual violence, including rape, the survey of 1,559 teenagers found, while 31 per cent have witnessed it happen.
So-called revenge porn was also shown to be prevalent among children, with 51 per cent of those surveyed, aged between 13 and 17, having seen it circulated.
Revenge porn was recently outlawed by the Government and is defined as the sharing of private, often sexual or explicit material, photos or videos, of another person without their consent.
Nearly a quarter of teenagers (23 per cent), meanwhile, know of someone secretly taking sexual images of another person and sharing it online, according to the research.
The Childnet report examines sexual harassment in four categories, non-consensual sharing of explicit material, threats and coercion, sexualised bullying and unwanted sexualisation.
Its release comes as the Government prepares new guidance on sexual harassment in schools, work on which was due to start in November, schools minister Nick Gibb previously said.
Will Gardner, chief executive of Childnet, said ahead of the report’s launch at the Children’s Global Media Summit in Manchester: "Digital technology plays a central role in young people’s lives but it has opened the door for a range of new forms of sexual harassment, making societal discussions about these issues more pertinent than ever.
"It is evidently something that as a society we can no longer ignore.
"Throughout the development of this report we have listened to the stories of young people who are navigating the complexities of relationships in a digital age and in some cases are facing the worst forms of peer-to-peer victimisation and online sexual harassment."
Among the other findings made by the report was that more than a quarter of UK teenagers had been the victim of online rumours about their sexual behaviour. And 12 per cent of teenagers claimed they had been pressured by their partner into sharing nude images. Many have also had sexual comments posted on images they shared of themselves online, a problem reported by 33 per cent of girls and 14 per cent of boys.
Fake profiles have become a common way for offenders to circulate sexual material, the study found. Almost a third of teens had seen such profiles, while 47 per cent had witnessed "doxing", the practice of sharing the personal details of someone, often whom they view as "easy".